Process for selecting single colors or color tones from pictures comprising several colors or color tones, especially for reproduction purposes



May 16, 1939. 5z|GET| 2,158,951

PROCESS FOR SELECTING GLE COLORS O OLOR TONES FROM I PICTURES COMPRISING SEVERAL COLORS CO R TONES, ESPECIALLY FOR REPRODUCTION PURPO S Filed March 2, 1936 E2 .1" 1 1| l' I Hill ig I Patented May 16,: 1939 I l rg-p SATAITES' PATENT OFFICE PROCESS FOR SELECTING SINGLE COLORS OR. COLOR TONES FROM PICTURES COM- PRISING SEVERAL COLORS OR COLOR TONES, ESPECIALLY FOR REPRODUCTION PURPOSES Ladisl aus Szigeti, Ujpest, Hungary Application March 2, 1936, Serial No. 66,758 In Hungary March 1, 1935 1 claim;

(Granted under the provisions of sec. 14, act or March 2, 1927; 35': o. G.

"In the reproducing industries it is often re .quired to select individual colors from the original multicolored drawings or pictures, which has been attained according to the processes hitherto Cknown, for instance in three color printing, by means of color filters and by proper choice of the period of exposure respectively- However, -;.it was not possible to select by these processes the colors only very slightly difiering from each other I 0' or the individual color tones thereof, that is to say to reproduce such a color tone in such a way that it shall be alone contained in the photograph. So for example the gray or violet spots of a pattern consisting of blackgray-white and red-violet-blue I colors. respectively could not be selected up till now but by means of long and expensive manual work. This is disadvantageous especially in the textile industry. where the ,colored fabrics in general are not producedby means of three color printing,

but the colors are mostly separately printed to the fabric, by which as many printing rollers and accordingly as many selections are required as:

the number of color tones of the pattern to be.

' reproduced, respectively as the number of color 25 tones of which the pattern should be made.

- The selection of the colors is eifected acc'orda ing to the invention without any manual work in av mere photographic way.

' Fig. 1 of the annexed drawing shows the original so pattern to be reproduced and Figs. 2 to 4 represent n the individual reproductions which correspond to the steps required for selecting a color tone in'accordance with the invention. Fig. 5 is a distorted cross section, of the reproduction according to 35 Fig- 2- The original pattern to be reproduced is usually I an ornamental one, however, for the sake of simplicity in Fig. 1 a pattern consisting of flvestrips of different color tones marked by running numo bers has been shown as the original pattern.

' The individual color tones are represented by corresponding hatching. Now, if from the different color tones that'indicated by 'the numeral 3 is to be selected, the pattern is photographed, that is.

45 to say the negative according to Fig. 2 is produced "by means of a suitable exposure or lighting through'and development with or without a color filter and eventually after interposing 'an'other layer. This negative is produced in such a way 60 that the color tone} to be.sclected isgiving a light gray image:on the negative, that is the sensitive layer of the plate is altered along the strip 3' in such a manner that on the outer limiting surface of the layer a thin protecting or covll ering layer 6 is produced (Fig. 5), however, the

, made, the reproduction according to Fig. 4 is obother parts of the layer or hardly changed. Namely, the sensitive layer is decomposed by the light before all at the spots where it is falling first to the said layer and by thisa protecting layer is produced. Thus by properly setting the exposure it may be attained that the reproduction 3" of the. color tone 3 to be selected is forming a transition between white and black, which is concolor tones 4 and 5 will become so dark that the chemical transformation is produced in the whole thickness of the layer or at least in its predominating part,

Consequently, when the reproduction obtained in the above described manner by means of exposure and development, before fixing, is once more exposed in a suitable way, that is to say it is acted upon bylight and this directly or after interposing a color filter or any other intermediate layer and afterwards this reproduction is again developed, the strips l' and 2' which have evidently not lost their sensitiveness oil-account of the development, will become much darker and y the strips 4' and 5' which have been dark already when taken. will be eventually somewhat further darkened. However, it has been found that the strip 3 keeps its original light gray color or it will be only very slightly darkened, as the protecting layer 6 being on its outer part prevents the penetration of light or it allows to pass such quantity of light only which causes a very slight darkening of the layer 3'. By this the reproduction. according to Fig. 3 is obtained, in which the strip 3" is pale and all other strips are dark respectively substantially darker than strip 3", Now, if from this negative anadvantageouslyhard positive is tained inwhich only the'layer 3 resulting from tht light layer 3 is dark, that is to say clearly visible, whereas the strips l 2*, I! and 5 resulting from the dark strips I", 2", 4" and 5", if they are discernible at all, are so light that they do not at all disturb the reproduction. Thus, by the aid of this method a reproduction of the original picture is obtained, in which only the color spots produced with the color tone to be of the 5 original picture are contained, that is to say the desired selection has been fulfilled.

It has been mentioned that the second exposure must be a "suitable one, and since the protecting layer B is not opaque, but only partially obstructs passage of light rays, it will be understood that the intensity of the second exposure: must be so chosen as to be strong enough for darkening the parts I and I", but not :so strong that the light rays will penetrate underneath the covering layer 6. Of course, if the intensity of the second exposure is too great, that is to say the plate is exposed to light for too long a period, the light rays penetrate through layer 8 and strip 3' will be as darkas strips l' and 2'.

It is obvious that the second exposure is to be i made from the emulsion side:

I exposure an out of focus image of the original From the'diiferent embodiments of the invented process I would mention that the plate or film may be in the. developing liquid during the exposure or it may be dipped into the said developing liquid before exposure, by which the devel- According to the above explanations this proc css is based upon the discovery that the gray tones of a developed but not fixed photographic reproduction are not considerably altered by a second properly chosen exposure and development. However, this discovery can be utilised not only in connection with the above mentioned selection, but it offers great many possibilities of use, which are mostly closelyconnected to selection. It is for example well known that in certain printing processes, especially in the textile industry, where owing to the dilute colors in use, furthermore, to the great absorptive capacity of the cloth to be coloredthe spots will become enlarged, all lines are to be made thinner and all spots' smaller than they have been in the original pattern. Thus besides the selection also'a reduced reproduction is to be made, in which all color spots are smaller than in the original image This object is attained by means of the above principle in such a way that at the first pattern is made or in any other way (by means of solarisation, etc.) provision is made that between the white and black colors a gray transition is obtained. Then this picture is once more exposed and developed in the above described way. At the second exposure only the part of the spots which is within the gray strips will become darker, that is around the individual color spots a gray limiting strip provided with tween the light (negative) color spots'produced by the first exposure should be rendered pale,

for instance by means of a silver solvent employed before the second exposure; should it not be so, after the .second exposure the color spots would be just as dark as the background and only the limiting strip would be pale. However, after using the silver solvent, the background will have the same'color as the limiting strips and the reduced spots only will be dark. I

The principle of double exposure and double development is also adapted for coloring the images, as if at both exposures differently colored images are produced, a two-colored reproduction may be obtained. Moreover, the exposure may be done through any figure (design) ,for instance through a reticulation, by which further color effects can be attained.

I claim:

Process for manufacturing printing means-for,

ture to be altered; developing the reproduction to obtain an image on which the said parts corresponding to the selected color or tone are more light than the other parts; fixing this picture image and making a hard positive from said image. LADISLAUS SZIGETI. 

